| ∀ x. ∃ z, x0, y1. x = z + x0 ∧ y0 = z + y1 ∧ (x0 ≠ [] ∧ y1 ≠ [] → x0.first ≠ y1.first) ⊦ a = a0, ∃ z, x, y. a0 ' + x1 = z + x ∧ a ' + y0 = z + y ∧ (x ≠ [] ∧ y ≠ [] → x.first ≠ y.first) |
Used simplifier rules: Nil: ⊦ [] + x = x;%a: ⊦ (x + y) + z = x + y + z;%app-08: ⊦ a ' + x = a ' + y ↔ x = y;%e-01: ⊦ a ' + x ≠ [];%c-08: ⊦ (a ' + x).first = a; Used terms: [], a0 ' + x1, a ' + y0